8790 A Case Of Ectopic Cushing’s Syndrome Secondary To Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia (DIPNECH)

Abstract Disclosure: T. Goettemoeller: None. R. Lopez Fanas: None. K. Cedeno: None. A. Manavalan: None. Introduction: Ectopic Cushing’s syndrome is a rare disease accounting for <20% of cases of endogenous Cushing’s syndrome. DIPNECH is a poorly understood lung disease characterized by abnormal proliferation of neuroendocrine cells in the bronchial mucosa. It can be a precursor to pulmonary carcinoid tumors and has rarely been associated with ACTH production. Clinical Case: A 70-year-old female with intellectual disability and hypertension presented with diffuse edema and weakness. Examination was notable for hypertension, anasarca, and hirsutism. In addition to hypokalemia and metabolic alkalosis, hypercortisolism was observed: random serum cortisol - 50.1 ug/dL, late-night salivary cortisol - 1.72 mcg/dL (normal < 0.09 mcg/dL) and 24-hour urine free cortisol - 1,845.9 mcg (normal: 4.0 – 50.0 mcg/24h). Cortisol level remained > 25 ug/dL after high-dose dexamethasone suppression test. Ketoconazole was initiated and titrated to achieve normal 24-hour urine free cortisol levels and spironolactone was added to manage hypokalemia. An MRI of the sella and pituitary was unremarkable while an abdomen and chest CT identified a 2.5 cm well-circumscribed right middle lobe pulmonary nodule and mild thickening of the bilateral adrenal glands. A gallium-DOTATATE scan revealed a 2.1 cm right middle lobe pulmonary nodule with mildly increased uptake. A transbronchial biopsy of the right middle lobe nodule confirmed a carcinoid tumor. Immunohistochemistry (IHC) staining was positive for CHR, SYN, CD56, and AE1/3. Ki-67 stain showed a low proliferative index. A right middle lobectomy was performed with pathology revealing two typical carcinoid tumors measuring 2.8 and 0.7 cm each, with multiple carcinoid tumorlets and foci of neuroendocrine cell hyperplasia consistent with DIPNECH. IHC staining for ACTH was positive in the carcinoid tumors and tumorlets. Four days after surgery, AM cortisol was 8.1 ug/dL and potassium levels and blood pressure normalized off ketoconazole and spironolactone. The patient was discharged, but was readmitted a month later for anasarca, lethargy, hypokalemia, and metabolic alkalosis. A recurrence of Cushing’s syndrome was confirmed, and medical therapy was resumed. A chest CT revealed post-surgical changes. Her course was complicated by an aspiration event, septic shock, PEA arrest, resuscitation, and intubation. The patient’s care was ultimately transitioned to hospice. Conclusion: Florid Cushing’s syndrome due to ectopic ACTH production associated with DIPNECH is an exceedingly rare condition. Early recognition and treatment are crucial to prevent the numerous complications that may arise, and close follow-up after tumor removal is critical to ensure continued remission has been achieved. Presentation: 6/1/2024